In this work we analyze a sample of AGN spectra, selected from the 6 Data Release of the Sloan Digital Sky Survey, exploiting a generalized technique of line profile analysis, designed to take into account the whole profiles of their broad emission lines. We find that the line profile broadening functions result from a complex structure, but we may be able to infer some constraints about the ro...

It is argued that supermassive black holes in the nuclei of galaxies most likely have grown coevally with their host dark matter halos. A calculation based on PressSchechter within this framework shows that the mean rate of accretion of matter onto such black holes varies from a value about 0.003 of the Eddington rate at the present epoch to a value around 0.08 at redshift 3. The bulk of AGN ev...

We present the results of a multi-epoch radio monitoring campaign measuring the milliarcsecond structure of the jet in the radio-quiet quasar PG1407+263. This is the highest-sensitivity, highestresolution multi-year study of a distant active galaxy. The observations are naturally explained in terms of a beamed relativistic jet, some of whose fluctuations in flux density can be ascribed to inter...

The relationship of an AGN to its host galaxy is a crucial question in the study of galaxy evolution. We perform stellar population synthesis in the central regions of galaxies of different activity levels. A large number of stellar features are measured both in the optical and near-infrared. We find the nuclear stellar population to be related to the level of activity. These differences are no...

Global millimetre VLBI allows detailed studies of the most central jet regions of AGN with unprecedent spatial resolution of a few 100–1000 Schwartzschild radii to be made. Study of these regions will help to answer the question how the highly relativistic AGN jets are launched and collimated. Since the early 1990s, bright mm-sources have been observed with global 3 mm VLBI. Here we present new...

A significant correlation between FeKα line energy and X-ray spectral slope has been discovered among radio-quiet active galactic nuclei. The ionization stage of the bulk of the FeKα emitting material is not the same in all active galactic nuclei and is related to the shape of the X-ray continua. Active galactic nuclei with a steep X-ray spectrum tend to have a fluorescence FeKα line from highl...

In this paper, analytical arguments are presented that there exists a synchrotron X-ray jet on large scales in most radio-loud AGNs, based on the knowledge of the nature and physics of blazars. In blue blazars and blue-blazar-like radio galaxies, the large scale X-ray jet may get faint along the jet, while in most red blazars and red-blazar-like radio galaxies, the X-ray jet is bright on 10 kpc...

The universality of the globular cluster luminosity function (GCLF) contrasts the variation seen in the specific frequency (SN). The variation in SN has been shown to follow a linear relation with LX for brightest cluster galaxies Blakeslee 1997. Further, the variation of SN with galactic radius within individual giant ellipticals is seen to be a constant fraction of the gas density McLaughlin ...

We present observations of the 22 GHz water vapor megamasers in the Circinus galaxy made with the Tidbinbilla 70 m telescope. These observations confirm the rapid variability seen earlier by Greenhill et al. (1997). We show that this rapid variability can be explained by interstellar scintillation, based on what is now known of the interstellar scintillation seen in a significant number of flat...

The observed apparent velocities and luminosities of the relativistic jets in AGNs are significantly different from their intrinsic values due to strong special relativistic effects. We adopt the maximum likelihood method to determine simultaneously the intrinsic luminosity function and the Lorentz factor distribution of a sample of AGNs. The values of the best estimated parameters are consiste...